There's nothing new about how to create zfs pools, basically the same as btrfs for example, you just choose zfs and the profile you want:

 

• O main click "add pool"
• choose the pool name and number of slots
• click on the pool and change the filesystem to zfs and select the profile you want to use
• start the array format the pool

done

my only other solution is to edit the smb file.
 

If you have a mount point /mnt/zfs_pool name

you can use smb extra in teh web UI and make your own samba share.

its be a weird workaround.